Improve behavior of date_bin with origin in the future

Currently, when the origin is after the input, the result is the
timestamp at the end of the bin, rather than the beginning as
expected.  This puts the result consistently at the beginning of the
bin.

Author: John Naylor 
Discussion: https://www.postgresql.org/message-id/CAFBsxsGjLDxQofRfH+d4KSAXxPf3MMevUG7s6EDfdBOvHLDLjw@mail.gmail.com

diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index b2bdbcab5766915a256b9e605ba21ee896213295..280ee7f92bab83ea750cc5df0bbf8b326f7030de 100644 (file)
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -3846,6 +3846,13 @@ timestamp_bin(PG_FUNCTION_ARGS)
    tm_diff = timestamp - origin;
    tm_delta = tm_diff - tm_diff % stride_usecs;
 
+   /*
+    * Make sure the returned timestamp is at the start of the bin,
+    * even if the origin is in the future.
+    */
+   if (origin > timestamp && stride_usecs > 1)
+       tm_delta -= stride_usecs;
+
    result = origin + tm_delta;
 
    PG_RETURN_TIMESTAMP(result);
@@ -4017,6 +4024,13 @@ timestamptz_bin(PG_FUNCTION_ARGS)
    tm_diff = timestamp - origin;
    tm_delta = tm_diff - tm_diff % stride_usecs;
 
+   /*
+    * Make sure the returned timestamp is at the start of the bin,
+    * even if the origin is in the future.
+    */
+   if (origin > timestamp && stride_usecs > 1)
+       tm_delta -= stride_usecs;
+
    result = origin + tm_delta;
 
    PG_RETURN_TIMESTAMPTZ(result);

diff --git a/src/test/regress/expected/timestamp.out b/src/test/regress/expected/timestamp.out
index 690656dfb2daede90f88bf06dfd9b89fab82d1c9..ac1a4a9b6acad6c46b2cb2927438cce2cdf557ae 100644 (file)
--- a/src/test/regress/expected/timestamp.out
+++ b/src/test/regress/expected/timestamp.out
@@ -609,6 +609,60 @@ FROM (
  microsecond | 1 us     | t
 (7 rows)
 
+-- case 3: AD dates, origin > input
+SELECT
+  str,
+  interval,
+  date_trunc(str, ts) = date_bin(interval::interval, ts, timestamp '2020-03-02') AS equal
+FROM (
+  VALUES
+  ('week', '7 d'),
+  ('day', '1 d'),
+  ('hour', '1 h'),
+  ('minute', '1 m'),
+  ('second', '1 s'),
+  ('millisecond', '1 ms'),
+  ('microsecond', '1 us')
+) intervals (str, interval),
+(VALUES (timestamp '2020-02-29 15:44:17.71393')) ts (ts);
+     str     | interval | equal 
+-------------+----------+-------
+ week        | 7 d      | t
+ day         | 1 d      | t
+ hour        | 1 h      | t
+ minute      | 1 m      | t
+ second      | 1 s      | t
+ millisecond | 1 ms     | t
+ microsecond | 1 us     | t
+(7 rows)
+
+-- case 4: BC dates, origin > input
+SELECT
+  str,
+  interval,
+  date_trunc(str, ts) = date_bin(interval::interval, ts, timestamp '0055-06-17 BC') AS equal
+FROM (
+  VALUES
+  ('week', '7 d'),
+  ('day', '1 d'),
+  ('hour', '1 h'),
+  ('minute', '1 m'),
+  ('second', '1 s'),
+  ('millisecond', '1 ms'),
+  ('microsecond', '1 us')
+) intervals (str, interval),
+(VALUES (timestamp '0055-6-10 15:44:17.71393 BC')) ts (ts);
+     str     | interval | equal 
+-------------+----------+-------
+ week        | 7 d      | t
+ day         | 1 d      | t
+ hour        | 1 h      | t
+ minute      | 1 m      | t
+ second      | 1 s      | t
+ millisecond | 1 ms     | t
+ microsecond | 1 us     | t
+(7 rows)
+
 -- bin timestamps into arbitrary intervals
 SELECT
   interval,

diff --git a/src/test/regress/sql/timestamp.sql b/src/test/regress/sql/timestamp.sql
index c43a1f22688f3abaaa7d6def6a02a82f0ad884f4..d51e83127aee96ceb620c2f29db62ab67e7ec72c 100644 (file)
--- a/src/test/regress/sql/timestamp.sql
+++ b/src/test/regress/sql/timestamp.sql
@@ -203,6 +203,40 @@ FROM (
 ) intervals (str, interval),
 (VALUES (timestamp '0055-6-10 15:44:17.71393 BC')) ts (ts);
 
+-- case 3: AD dates, origin > input
+SELECT
+  str,
+  interval,
+  date_trunc(str, ts) = date_bin(interval::interval, ts, timestamp '2020-03-02') AS equal
+FROM (
+  VALUES
+  ('week', '7 d'),
+  ('day', '1 d'),
+  ('hour', '1 h'),
+  ('minute', '1 m'),
+  ('second', '1 s'),
+  ('millisecond', '1 ms'),
+  ('microsecond', '1 us')
+) intervals (str, interval),
+(VALUES (timestamp '2020-02-29 15:44:17.71393')) ts (ts);
+
+-- case 4: BC dates, origin > input
+SELECT
+  str,
+  interval,
+  date_trunc(str, ts) = date_bin(interval::interval, ts, timestamp '0055-06-17 BC') AS equal
+FROM (
+  VALUES
+  ('week', '7 d'),
+  ('day', '1 d'),
+  ('hour', '1 h'),
+  ('minute', '1 m'),
+  ('second', '1 s'),
+  ('millisecond', '1 ms'),
+  ('microsecond', '1 us')
+) intervals (str, interval),
+(VALUES (timestamp '0055-6-10 15:44:17.71393 BC')) ts (ts);
+
 -- bin timestamps into arbitrary intervals
 SELECT
   interval,